Trivial clean up: do not use plural form in command arguments.

It is a general rule that we don't use plural form for the name of
command arguments. But class DeleteServer() is still using "servers".
So use "server instead".

Change-Id: I2d76de14ec34b88547b9f728b41e9bd93b2a22c5

Author: tang-chen

openstackclient/compute/v2/server.py

@@ -607,7 +607,7 @@ class DeleteServer(command.Command):
     def get_parser(self, prog_name):
         parser = super(DeleteServer, self).get_parser(prog_name)
         parser.add_argument(
-            'servers',
+            'server',
             metavar='<server>',
             nargs="+",
             help=_('Server(s) to delete (name or ID)'),
@@ -622,7 +622,7 @@ def get_parser(self, prog_name):
     @utils.log_method(log)
     def take_action(self, parsed_args):
         compute_client = self.app.client_manager.compute
-        for server in parsed_args.servers:
+        for server in parsed_args.server:
             server_obj = utils.find_resource(
                 compute_client.servers, server)
             compute_client.servers.delete(server_obj.id)

openstackclient/tests/compute/v2/test_server.py

@@ -311,7 +311,7 @@ def test_server_delete_no_options(self):
             compute_fakes.server_id,
         ]
         verifylist = [
-            ('servers', [compute_fakes.server_id]),
+            ('server', [compute_fakes.server_id]),
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
@@ -328,7 +328,7 @@ def test_server_delete_wait_ok(self, mock_wait_for_delete):
             compute_fakes.server_id, '--wait'
         ]
         verifylist = [
-            ('servers', [compute_fakes.server_id]),
+            ('server', [compute_fakes.server_id]),
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
@@ -351,7 +351,7 @@ def test_server_delete_wait_fails(self, mock_wait_for_delete):
             compute_fakes.server_id, '--wait'
         ]
         verifylist = [
-            ('servers', [compute_fakes.server_id]),
+            ('server', [compute_fakes.server_id]),
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)